Maltitol is, as described in Japan Patent Publication No. 13,699/72 (MITSUHASHI et al.), obtained by reduction of maltose, and has a sweetness which is close in quality to that of sucrose, and a sweetening power about 75% higher than that of sucrose.
Since maltitol is hardly absorbable and utilizable in the digestive system, and hardly fermentable by oral microorganisms, it has been used as a sweetener for low-caloric, dietary, low-cariogenic and health foods for diabetics, obese persons and those who are conscious of their health, including dental health.
However, since maltitol in dry solid form is extremely hygroscopic and deliquescent, and difficult to prepare into powder, it has usually been handled only in the form of an aqueous solution; thus, its use has been extremely restricted. For example, amorphous, substantially-anhydrous candies can be obtained by boiling down an aqueous maltitol solution at 180.degree.-190.degree. C., but the candies must be stored in a moisture proof vessel together with desiccant due to their high hygroscopicity and deliquescence; thus, the handling of such candies renders great difficulties.
As to the hygroscopic properties of maltitol, M. J. Wolfrom et al. have reported in J. Am. Chem. Soc., Vol.62, pp.2553-2555 (1940), that maltitol had been obtained only in the form of an amorphous, white, hygroscopic solid; and J. E. Hodge et al. have reported in Cereal Science Today, Vol.17, No.7, pp.180-188 (1972) that they had not yet obtained a nonhygroscopic solid form of maltitol and that maltitol could be crystallized as a hygroscopic ethanol complex.
As obvious from the above descriptions, only a highly hygroscopic maltitol solid has been hitherto known.
Recently, many attempts to reduce the high hygroscopicity of maltitol as much as possible, and also to obtain a maltitol in powder form have been reported. For example, Japan Kokai No. 477/74 (UENO, Kunio et al.) and 87,619/74 (HIDAKA, Yoshio et al.) disclose processes for the production of maltitol powder by admixing a hydrophilic polymer, such as an edible polymer, to an aqueous maltitol solution, and drying up the mixture to obtain the objective powder. Japan Kokai No. 59,312/75 (HISANO, Kazuaki et al.) discloses a process for the production of maltitol powder which comprises mixing a composition containing maltitol with a small amount of one or more members of mono-saccharides or their sugar alcohol derivatives, melting the mixture by heating to anhydrous fusion form, cooling the resultant, and spray-drying and fluidizing in a moisture proof tower to obtain the objective maltitol powder. Japan Kokai No. 110,620/74 (HIRAIWA, Takashi), 24,206/75 (HIRAIWA, Takashi et al.), 25,514/75 (OYAMADA, Ko-ichiro et al.), 32,745/76 (HIRAIWA, Takashi), 106,766/76 (HIRAIWA, Takashi), 113,813/76 (HIRAIWA, Takashi), 128,441/76 (HIRAIWA, Takashi) and 47,928/77 (HIRAIWA, Takashi) disclose processes for the production of maltitol powder which comprise pulverizing maltitol solids under dried air conditions, and coating the resultant maltitol powder with other edible powders. Japan Kokai No. 29,510/75 (KANE-EDA, Jun et al.) discloses a method for preventing consolidation of powder containing maltitol wherein a powder containing maltitol is moistened with a solvent which substantially indissolves maltitol, and dried together with other sugar micro-powder under mixing conditions to apply coating on the particles of maltitol powder with the micro-powder.
All attempts have proved, however, unsuccessful because maltitol must be mixed with a large amount of other substance(s) or coated therewith, and the high hygroscopicity of maltitol cannot be eliminated thereby. In effect, the maltitol powder obtained by any of the above described processes or methods barely retains its powder form under ambient conditions, and still exhibits its high hygroscopicity; therefore, it is readily susceptible to moisture-absorption, consolidation and/or deliquescence under ambient conditions within a short time, and is not utilizable for practical uses.